The invention relates to a method for energy management as claimed in claim 1.
Due to the increasing need for electrical energy in vehicles, for example due to drive-by-wire technology, and the resulting substantial fluctuations in the behavior through time of energy consumption, a method for energy management becomes increasingly important. In a method of this type, it must noted in particular that the capability of the system to deliver sufficient electrical energy at any time is to a significant extent relevant to safety.
For example, a method for activating and deactivating different classes of consumers by means of switching elements in the context of energy management performed by a control device, particularly in a motor vehicle, is known from DE 199 60 079 A1. The switching elements are controlled in such a way that the selected priorities for controlling the switching elements can be changed during operation, i.e. dynamically. Operating-mode-dependent adaptation of switching priorities during live operation is therefore possible. Consumers are deactivated by changing the switching priority in such a way that the perceptibility of the operating modes is suppressed as much possible. Priorities can also be changed here according to specifically customized criteria.
In this and other hitherto known methods for energy management, the problem exists that they are, inter alia, inadequate, given that, in the case of on-board electrical systems with one or two current circuits, an entire current circuit is deactivated in each case, or they are highly complex in terms of their logic and are subsequently difficult to expand. In methods of this type, consumers are often switched according to a statically or dynamically defined priority. Although this takes account very effectively of the aspect of operational reliability, the convenience and acceptance of the driver are only considered indirectly. For the driver, the time between the switching command and execution is of primary importance. Furthermore, in the method described above, energy management is only performed reactively, i.e. consumers are only deactivated once an energy shortfall has occurred. In this case, consumers such as electric motors have already started up and have imposed a load on the battery through the start-up current flow. It is not possible to control on-board electrical system components predicatively.
The object of the present invention is therefore to further develop a method for energy management of the generic type in such a way that predictive control of on-board electrical system components is possible, so that the imposition of a load on the battery by consumers which are to be deactivated immediately is avoided. Furthermore, the time span that elapses between the switching command and execution and the maximum time span that may elapse in the switching/activation sequence are to be directly taken into account.